1. Field
Example embodiments relate to image sensors and methods of fabricating the same.
2. Description of the Related Art
Image sensors convert optical images into electrical signals. Recent developments in the computer industry and telecommunications industry have led to an increase in demand for high performance image sensors in various applications including digital cameras, camcorders, Personal Communication System (PCS), security cameras, and medical microcameras.
In particular, a MOS image sensor can be readily driven and implemented with various scanning techniques. Further, use of a MOS image sensor will reduce the size of a product since signal processing circuits are integrated into a single chip while lowering the manufacturing cost because a MOS process technology can be compatibly used. With low power consumption, MOS image sensors can be easily applied to battery-powered products. Thus, due to advances in technology and implementation of high resolution, the use of MOS image sensors has rapidly increased.
A MOS image sensor includes a photoelectric transformation unit that senses the magnitude of incident light and a plurality of metal interconnect layers that output optical signals stored in the photoelectric transformation unit. Since the incident light is reflected by the metallic wire layers or absorbed by an interlayer dielectric layer, the sensitivity of the MOS image sensor may be degraded. Further, the reflected light may be absorbed into neighboring pixels, thereby causing crosstalk between the pixels.
Therefore, in order to solve the above problems, a back side illuminated (BI) image sensor has been recently proposed in which a back side of a substrate is polished and light is incident from a front side of the substrate. Because the BI image sensor has no metallic wire layer formed on the front side from which light is incident, the incident light cannot be reflected by a metallic wire layer nor absorbed by an interlayer dielectric layer.